The present invention relates to clutch plates in general, and more particularly to improvements in clutch plates which can be used in friction clutches of automotive vehicles. Still more particularly, the invention relates to improvements in clutch plates of the type wherein a hub (which can transmit torque to the input shaft of a change-speed transmission) carries two disc-shaped walls which flank a carrier for friction linings. The linings are installed between the flywheel of an automotive vehicle and a pressure plate of the friction clutch to transmit torque from the flywheel to the hub or vice versa. As a rule, the carrier is free to perform limited angular movements with reference to the hub against the opposition of energy storing elements in the form of coil springs or the like.
A clutch plate of the above outlined character is disclosed, for example, in German Auslegeschrift No. 19 18 110 wherein the carrier of friction linings comprises two flat discs which are disposed between the walls on the hub and flank the inner portion of a further disc whose outer portion carries the friction linings. The purpose of the flat discs is to reinforce the carrier, and the further disc extends radially inwardly all the way from the outer to the inner marginal portions of the flat discs. A drawback of such clutch plates is that they are bulky, i.e., their inertia is very pronounced. This is attributable, to a considerable degree, to the dimensions and mass of the further disc whose inner marginal portion is immediately adjacent to the hub and whose outer marginal portion is disposed at a considerable distance from the outer marginal portions of the walls and of the flat discs. The bulk and inertia of the clutch plate contribute to complexity of the synchronizing unit of the transmission which cooperates with and normally receives torque from the clutch plate. Also, the wear upon the transmission is quite pronounced because the transmission must transmit substantial loads due to the bulk and inertia of the carrier of friction linings and hence of the entire clutch plate.
Another drawback of the just described conventional clutch plates is that their manufacturing cost is very high. This is due, to a considerable extent, to the fact that the further disc of the carrier of friction linings is a complete annulus having a large outer diameter. The making of large-diameter annuli from sheets of metallic material entails considerable losses in such material due to the presence of large remnants which develop even if the removal of annuli (e.g., by resorting to a stamping or like machine) leaves the remaining portion of a sheet with holes which are immediately adjacent to each other.